Backport of added check if anonymous token policy exists into release/1.2.x

.changelog/2790.txt

@@ -0,0 +1,3 @@
+```release-note:improvement
+control-plane: prevent updation of anonymous-token-policy and anonymous-token if anonymous-token-policy is already attached to the anonymous-token
+```

control-plane/subcommand/server-acl-init/anonymous_token.go

@@ -7,9 +7,24 @@ import (
 	"github.com/hashicorp/consul/api"
 )
 
+const (
+	anonymousTokenPolicyName = "anonymous-token-policy"
+	anonymousTokenAccessorID = "00000000-0000-0000-0000-000000000002"
+)
+
 // configureAnonymousPolicy sets up policies and tokens so that Consul DNS and
 // cross-datacenter Consul connect calls will work.
 func (c *Command) configureAnonymousPolicy(consulClient *api.Client) error {
+	exists, err := checkIfAnonymousTokenPolicyExists(consulClient)
+	if err != nil {
+		c.log.Error("Error checking if anonymous token policy exists", "err", err)
+		return err
+	}
+	if exists {
+		c.log.Info("skipping creating anonymous token since it already exists")
+		return nil
+	}
+
 	anonRules, err := c.anonymousTokenRules()
 	if err != nil {
 		c.log.Error("Error templating anonymous token rules", "err", err)
@@ -18,7 +33,7 @@ func (c *Command) configureAnonymousPolicy(consulClient *api.Client) error {
 
 	// Create policy for the anonymous token
 	anonPolicy := api.ACLPolicy{
-		Name:        "anonymous-token-policy",
+		Name:        anonymousTokenPolicyName,
 		Description: "Anonymous token Policy",
 		Rules:       anonRules,
 	}
@@ -33,7 +48,7 @@ func (c *Command) configureAnonymousPolicy(consulClient *api.Client) error {
 
 	// Create token to get sent to TokenUpdate
 	aToken := api.ACLToken{
-		AccessorID: "00000000-0000-0000-0000-000000000002",
+		AccessorID: anonymousTokenAccessorID,
 		Policies:   []*api.ACLTokenPolicyLink{{Name: anonPolicy.Name}},
 	}
 
@@ -44,3 +59,18 @@ func (c *Command) configureAnonymousPolicy(consulClient *api.Client) error {
 			return err
 		})
 }
+
+func checkIfAnonymousTokenPolicyExists(consulClient *api.Client) (bool, error) {
+	token, _, err := consulClient.ACL().TokenRead(anonymousTokenAccessorID, nil)
+	if err != nil {
+		return false, err
+	}
+
+	for _, policy := range token.Policies {
+		if policy.Name == anonymousTokenPolicyName {
+			return true, nil
+		}
+	}
+
+	return false, nil
+}

control-plane/subcommand/server-acl-init/anonymous_token_test.go

@@ -0,0 +1,68 @@
+package serveraclinit
+
+import (
+	"strings"
+	"testing"
+
+	"github.com/hashicorp/consul/api"
+	"github.com/mitchellh/cli"
+	"github.com/stretchr/testify/require"
+)
+
+func Test_configureAnonymousPolicy(t *testing.T) {
+
+	k8s, testClient := completeSetup(t)
+	consulHTTPAddr := testClient.TestServer.HTTPAddr
+	consulGRPCAddr := testClient.TestServer.GRPCAddr
+
+	setUpK8sServiceAccount(t, k8s, ns)
+	ui := cli.NewMockUi()
+	cmd := Command{
+		UI:        ui,
+		clientset: k8s,
+	}
+	cmd.init()
+	flags := []string{"-connect-inject"}
+	cmdArgs := append([]string{
+		"-timeout=1m",
+		"-resource-prefix=" + resourcePrefix,
+		"-k8s-namespace=" + ns,
+		"-auth-method-host=https://my-kube.com",
+		"-addresses", strings.Split(consulHTTPAddr, ":")[0],
+		"-http-port", strings.Split(consulHTTPAddr, ":")[1],
+		"-grpc-port", strings.Split(consulGRPCAddr, ":")[1],
+	}, flags...)
+	responseCode := cmd.Run(cmdArgs)
+	require.Equal(t, 0, responseCode, ui.ErrorWriter.String())
+
+	bootToken := getBootToken(t, k8s, resourcePrefix, ns)
+	consul, err := api.NewClient(&api.Config{
+		Address: consulHTTPAddr,
+		Token:   bootToken,
+	})
+	require.NoError(t, err)
+
+	err = cmd.configureAnonymousPolicy(consul)
+	require.NoError(t, err)
+
+	policy, _, err := consul.ACL().PolicyReadByName(anonymousTokenPolicyName, nil)
+	require.NoError(t, err)
+
+	testPolicy := api.ACLPolicy{
+		ID:          policy.ID,
+		Name:        anonymousTokenPolicyName,
+		Description: "Anonymous token Policy",
+		Rules:       `acl = "read"`,
+	}
+	readOnlyPolicy, _, err := consul.ACL().PolicyUpdate(&testPolicy, &api.WriteOptions{})
+	require.NoError(t, err)
+
+	err = cmd.configureAnonymousPolicy(consul)
+	require.NoError(t, err)
+
+	actualPolicy, _, err := consul.ACL().PolicyReadByName(anonymousTokenPolicyName, nil)
+	require.NoError(t, err)
+
+	// assert policy is still same.
+	require.Equal(t, readOnlyPolicy, actualPolicy)
+}